This application is a national stage of PCT/DE99/01410 filed May 10, 1998 under the International Convention
The invention relates to a semiconductor component with at least one lateral component for accommodating a lateral electric field strength, and to a method of making the semiconductor component and the use thereof.
In DE-A1-42 33 773 a microelectronic component in so-called SOI (Semiconductor-On-Insulator) technology is disclosed which has an enhanced breakdown voltage. The semiconductor component has a lateral component in a semiconductor body with a substrate whereby a dielectric zone is delimited on the substrate in which an electrically conductive region is embedded. The arrangement requires a technologically expensive adjustment of the buried structure with respect to the lateral component.
Furthermore, lateral as well as vertical components have been proposed which have on their surfaces structures which are provided to reduce the surface field strength to enhance the breakdown voltage. Such field plates or field rings also, however, give rise to an excessive technological cost in the production of such components.
it is the object of the invention to provide a semiconductor component and a method of making it which provides improved components with reference to the prior art described at the outset and especially affords higher breakdown voltages.
a semiconductor component of the invention has a semiconductor body and, at least in regions on this body and/or in layers disposed upon one another. The semiconductor body and/or in regions proximal to the surface of the semiconductor body at least in portions thereof there is a lateral three-dimensional structure which has vertical recesses in the semiconductor body within which the electrical conductivity is smaller than in the intervening spaces of the semiconductor body between the recesses.
A semiconductor component according to the invention has, in the semiconductor body and/or at least regionally in a surface-neighboring region of the semiconductor body a lateral three-dimensional structure which has vertical recesses in the semiconductor body in the interior of which the electrical conductivity is less than in the intervening spaces of the semiconductor body between the recesses.
In a preferred embodiment the semiconductor component is a lateral component with a dielectric zone bounding a substrate and between the dielectric zone and the semiconductor body the lateral three-dimensional structure is provided over at least a portion of the lateral component and is directly connected with the dielectric zone.
In an advantageous embodiment of the invention the three-dimensional structure has islands or lands which are separated by vertical recesses from one another, whereby the electrical conductivity in the recesses is less than that in the islands or lands.
In a further advantageous embodiment of the invention the three-dimensional structure has ribs which are separated from one another by vertical recesses and whereby the electrical conductivity in the recesses is less than that in the ribs.
Advantageously in the semiconductor body over at least a region thereof a semiconductor of another material, especially polycrystalline material, can be disposed and which bounds the dielectric zone.
Advantageously, between the substrate and the dielectric zone, at least over a region thereof, a lateral semiconductor layer is provided.
In a further advantageous arrangement, between the substrate and the dielectric zone, at least over a region thereof, a lateral insulating layer is provided.
Advantageously, with a lateral component at least over a region, the width of the recesses in an imaginary sectional plane perpendicularly through the lateral component is smaller than 10% of the lateral drift stretch of the lateral component.
In a preferred embodiment, in a lateral component at least over a portion thereof, the width of the intervening spaces or interstices between neighboring recesses in an imaginary sectional plane perpendicularly through the lateral component is somewhat smaller than 30% of the lateral drift stretch.
An advantageous configuration of the invention provides that at least over part of the component, recesses in an imaginary sectional plane perpendicularly through the semiconductor component are approximately equidistant. This simplifies the manufacture of the component since no expensive technology steps are required and especially no adjustment of the structure relative to the lateral component is necessary.
A further preferred embodiment of the invention has at least in part a varying density of the recesses in an imaginary sectional plane perpendicularly through the semiconductor component. The breakdown voltage can be further increased in that the density of the recesses in different regions of the semiconductor body differs. It is especially advantageous below different functional regions of the component to provide different densities of the recesses.
Advantageously at least partially, the depths of the recesses can be greater than their breadths. At least in part the widths of the recesses can be smaller than the thickness of the dielectric zone. The special advantage is that with a comparable locking voltage the thickness of the dielectric zone of a component according to the invention can be smaller than with a conventional component. The thermal dissipation in the component according to the invention is improved as is the ability of the component according to the invention to withstand transitionally higher electric powers. It is also advantageous to provide at least in part widths of the recesses so that they will be smaller than the widths of the regions of the semiconductor body between the recesses.
The semiconductor body between the recesses represents zones which are interrupted by the recesses and in which electron or hole channels are formed and which in their electrostatic effects are already slightly removed from the region in which a continuous charge distribution appears so that field gradients and/or space charge zone curvature are reduced, thereby giving rise to an increase in the breakdown voltage.
An advantageous arrangement provides for the invention a semiconductor component with an edge structure for reducing the surface field strength of the component, whereby the edge structure on or in an outer surface of the semiconductor body at least neighboring an effective region of a space charge zone near the surface is arranged at a blocking contact in the semiconductor body whereby the semiconductor body at least in part at a surface has a lateral three-dimensional structure with vertical recesses in the interior of which the electrical conductivity is less than that of the semiconductor body.
In the method according to the invention for producing a component with a semiconductor body and a substrate, on a surface of the semiconductor body which is juxtaposed with the lateral component, initially at least in part, recesses are etched, the recesses are then filled with a material which is more highly ohmic than the material of the semiconductor body between the recesses and covered with a layer of a dielectric material and at least indirectly bonded with the substrate or provided with an oxide for connection with the surface of a substrate provided on the semiconductor body and at least partially provided with recesses in the oxide and filled with a semiconductor material and then covered with a layer of a semiconductor material and the covering layer at least indirectly arranged with the semiconductor body.
In a further process according to the invention for producing a component with an edge structure, recesses are provided at least partially in the surface of the semiconductor body whereby the recesses are filled with a dielectric or the surface of the semiconductor body is at least partially coated with an oxide, whereby recesses are formed in the oxide and filled with semiconductor material.
Especially advantageously, the recesses are applied substantially homogeneously over the surface region or entire semiconductor wafer. The advantage of the method of the invention is that no extensive technology is necessary for producing the lateral structure and especially there is no need for adjustment with respect to the lateral and/or vertical component in the semiconductor body.
The advantage of the lateral structure is that a field intensity in the semiconductor body or on the surface, the semiconductor body can be partly shielded so that the blocking behavior of the component is improved. The structure of the invention is especially suitable for components on a SOI basis (silicon-on-insulator) and also for vertical or lateral components which have field strength-reducing structures on the surface for reducing a surface field strength and/or the curvature of space-charge zones. Especially advantageous is the use of the invention in combination with field plates or field ring-like structures at the surface. Advantageous is the use of a component with lateral three-dimensional structuring in a driver circuit for power electronic converter systems. The voltage stability can be easily raised above 500 V so that use in networks with higher voltages, especially 220 volt networks or 380 volt three-phase networks, is possible.